scholarly journals Comparison of Selected Terramechanical Test Procedures and Cartographic Indices to Predict Rutting Caused by Machine Traffic during a Cut-to-Length Thinning Operation

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 113
Author(s):  
Marian Schönauer ◽  
Stephan Hoffmann ◽  
Joachim Maack ◽  
Martin Jansen ◽  
Dirk Jaeger
Keyword(s):  
Shear Strength ◽  
Penetration Depth ◽  
Sustainable Forest Management ◽  
Operating Conditions ◽  
Soil Conditions ◽  
Cone Penetration ◽  
Topographic Wetness Index ◽  
Mixed Stands ◽  
Thinning Operation ◽  
Cone Index

Timber harvesting operations using heavy forest machinery frequently results in severe soil compaction and displacement, threatening sustainable forest management. An accurate prediction of trafficability, considering actual operating conditions, minimizes these impacts and can be facilitated by various predictive tools. Within this study, we validated the accuracy of four terramechanical parameters, including Cone Index (MPa, Penetrologger), penetration depth (cm, Penetrologger), cone penetration (cm blow−1, dual-mass dynamic cone penetrometer) and shear strength (kPa, vane meter), and additionally two cartographic indices (topographic wetness index and depth-to-water). Measurements applying the four terramechanical approaches were performed at 47 transects along newly assigned machine operating trails in two broadleaved dominated mixed stands. After the CTL thinning operation was completed, measurement results and cartographic indices were correlated against rut depth. Under the rather dry soil conditions (29 ± 9 vol%), total rut depth ranged between 2.2 and 11.6 cm, and was clearly predicted by rut depth after a single pass of the harvester, which was used for further validations. The results indicated the easy-to-measure penetration depth as the most accurate approach to predict rut depth, considering coefficients of correlation (rP = 0.44). Moreover, cone penetration (rP = 0.34) provided reliable results. Surprisingly, no response between rut depth and Cone Index was observed, although it is commonly used to assess trafficability. The relatively low moisture conditions probably inhibited a correlation between rutting and moisture content. Consistently, cartographic indices could not be used to predict rutting. Rut depth after the harvester pass was a reliable predictor for total rut depth after 2–5 passes (rP = 0.50). Rarely used parameters, such as cone penetration or shear strength, outcompeted the highly reputed Cone Index, emphasizing further investigations of applied tools.

scholarly journals Rut Depth Evaluation of a Triple-Bogie System for Forwarders—Field Trials with TLS Data Support

2020 ◽  
Vol 12 (16) ◽  
pp. 6412
Author(s):  
Michael Starke ◽  
Cédric Derron ◽  
Felix Heubaum ◽  
Martin Ziesak
Keyword(s):  
Shear Strength ◽  
Laser Scanning ◽  
Sustainable Forest Management ◽  
Soft Soil ◽  
Ecological Impact ◽  
Digital Terrain Model ◽  
Soil Conditions ◽  
Soil Protection ◽  
Impact Machine ◽  
The Impact

In 2019, the machine manufacturer HSM presented a forwarder prototype for timber hauling in cut-to-length processes fitted with a new 10-wheel triple-bogie (TB) setup approach aimed at promoting sustainable forest management by reducing the ecological impact of forest operations, especially under soft-soil working conditions. The purpose of our study was to assess the resulting soil-protection effect emerging from additional wheel-contact surface area. For this, the rut development under known cumulative weight, related to the soil conditions of shear strength and moisture content, was recorded for later comparison. Additional terrestrial laser scanning (TLS) was used to generate a multi-temporal digital terrain model (DTM) in order to enhance the data sample, assess data quality, and facilitate visualization of the impact of local disturbance factors. In all TB configurations, a rut depth of 10 cm (5.8–7.2 cm) was not exceeded after the hauling of a reference amount of 90 m3 of timber (average soil shear strength reference of 67 kPa, volumetric water content (VMC) 43%). Compared to a reference dataset, all observed configurations ranked in the lowest-impact machine categories on related soil stability classes, and the configuration without bogie tracks revealed the highest machine weight to weight distribution trade-off potential.

scholarly journals Bond Strength between Glass Fiber Fabrics and Low Water-to-Binder Ratio Mortar: Experimental Characterization

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Daniel Bohling ◽  
Andrzej Cwirzen ◽  
Karin Habermehl-Cwirzen
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Bond Strength ◽  
Glass Fiber ◽  
Penetration Depth ◽  
Pullout Strength ◽  
Lap Shear Strength ◽  
Lap Shear ◽  
Binder Ratio ◽  
Water To Binder Ratio

Full utilization of mechanical properties of glass fiber fabric-reinforced cement composites is very limited due to a low bond strength between fibers and the binder matrix. An experimental setup was developed and evaluated to correlate the mortar penetration depth with several key parameters. The studied parameters included fresh mortar properties, compressive and flexural strengths of mortar, the fabric/mortar bond strength, fabric pullout strength, and a single-lap shear strength. Results showed that an average penetration of mortar did not exceed 100 µm even at a higher water-to-binder ratio. The maximum particle size of the used fillers should be below an average spacing of single glass fibers, which in this case was less than 20 µm to avoid the sieving effect, preventing effective penetration. The pullout strength was strongly affected by the penetration depth, while the single-lap shear strength was also additionally affected by the mechanical properties of the mortar.

Observations on some basal failures in sheeted excavations

1970 ◽  
Vol 7 (2) ◽  
pp. 136-144 ◽  
Author(s):  
V. Milligan ◽  
K. Y. Lo
Keyword(s):  
Shear Strength ◽  
Ground Water ◽  
Groundwater Level ◽  
Soil Conditions ◽  
Remedial Measures ◽  
Factors Influencing ◽  
Water Head ◽  
The Stability ◽  
Made In

In excavations below groundwater level, instability of the base may result from the inflow of water into the excavation. The most important factors influencing the stability are the ground water and detailed soil conditions at the site.Construction problems encountered in excavations in clay strata, underlain by pervious water bearing layers, are described. The remedial measures adopted in each case are also discussed. From a study of the observations made in the case records, it is suggested that excavation in intact clays may be carried out to depths exceeding that limited by the ratio of t/h = 0.5, where t is the distance from the bottom of the excavation to the top of the water bearing stratum, and h is the water head at the top of the water bearing stratum, provided that the clay is not disturbed during construction so that the shear strength of the clay is preserved.

Investigation on Flowfield and Fuel/Air Premixing Uniformities of Low Swirl Injector for Lean Premixed Gas Turbines

2021 ◽  
Author(s):  
Fujun Sun ◽  
Jianqin Suo ◽  
Zhenxia Liu
Keyword(s):  
Penetration Depth ◽  
Residence Time ◽  
Gas Turbines ◽  
Structural Parameters ◽  
Combustible Mixture ◽  
Operating Conditions ◽  
Flame Stability ◽  
Nox Emissions ◽  
Auto Ignition ◽  
Lean Premixed

Abstract Based on the development trend of incorporating fuel holes into swirler-vanes and the advantages of wide operating conditions as well as low NOx emissions of LSI, this paper proposes an original lean premixed LSI with a convergent outlet. The influence of key structures on flowfields and fuel/air premixing uniformities of LSI is investigated by the combination of laser diagnostic experiments and numerical simulations. The flowfields of LSI shows that the main recirculation zone is detached from the convergent outlet and its axial dimensions are smaller than that of HSI, which can decrease the residence time of high-temperature gas to reduce NOx emissions. The fuel/air premixing characteristics show that the positions and diameters of fuel holes affect fuel/air premixing by changing the penetration depth of fuel. And when the penetration depth is moderate, it can give full play to the role of swirling air in enhancing premixing of fuel and air. In addition, the increase of the length of the premixing section can improve the uniformity of fuel/ar premixing, but it can also weaken the swirl intensity and increase the residence time of the combustible mixture within the LSI, which can affect flame stability and increase the risk of auto-ignition. Therefore, the design and selection of LSI structural parameters should comprehensively consider the requirements of fuel/air mixing uniformity, flame stability and avoiding the risk of auto-ignition. The results can provide the technical basis for LSI design and application in aero-derivative and land-based gas turbine combustors.

Experimental Evaluation of Blasting Near Pipelines

2018 ◽  
Author(s):  
Justin Gossard ◽  
Steven A. Waters ◽  
Shane Finneran
Keyword(s):  
High Speed ◽  
Laser Scanning ◽  
Field Experiments ◽  
Separation Distance ◽  
Primary Objective ◽  
Operating Conditions ◽  
Soil Conditions ◽  
Exterior Surface ◽  
High Speed Video ◽  
Test Segment

Construction blasting was proposed as a technique to create a trench for a new pipeline within the right-of-way (ROW) of an existing vintage pipeline where soil conditions consisted primarily of rock. Several field experiments were conducted to assess the potential loading conditions that the vintage pipeline could experience due to various blasting configurations as part of the nearby construction process. Two test pipe segments were constructed from segments removed from the vintage pipeline for use in these experiments. Each test segment contained two vintage bell-bell chill ring girth welds (GW) and were pressurized to operating conditions of the vintage pipeline for the duration of all blasting. Groups of eight resistive strain gages were bonded around the exterior surface of three distinct locations on each test segment. The three locations include one pipe body location and each of the two welds on each segment. Four separate experiments were conducted with each experiment focusing on a unique combination of trench backfill material, compaction level and separation distance from the test pipe segments and the explosive charges. The primary objective throughout these four experiments was to monitor and record the behavior of buried test pipe sections due to nearby blasting activities. Long range 3-dimentional (3D) laser scanning equipment was used to track movement of each test segment from test to test. High-speed video equipment was also employed to capture each blast. The high-speed video provided additional details on the blast energy transfer, verification of individual charge initiation as well as pipeline test segment movement where each pipeline segment was exposed. Peak particle velocity measurements were taken during each test blast. Strain data collected during each test was used to assess potential damage to the vintage pipeline test segments as a result of blasting. The combined information collected from the in-field testing showed that elevated strains and stresses may be observed during blasting activities near pipelines.

Interpretation of cone penetration tests. Part II: Clay

1983 ◽  
Vol 20 (4) ◽  
pp. 734-745 ◽  
Author(s):  
P. K. Robertson ◽  
R. G. Campanella
Keyword(s):  
Shear Strength ◽  
Friction Angle ◽  
Companion Paper ◽  
Deformation Characteristics ◽  
Cone Penetration ◽  
Cone Penetration Tests ◽  
Cone Penetration Testing ◽  
Personal Experiences ◽  
Penetration Tests

This paper is the second of two parts and presents a summarized work guide for practicing engineers for interpretation of parameters for undrained conditions during the cone penetration test such as, undrained shear strength, overconsolidation ratio, and deformation characteristics of clay. The advantages, use, and interpretation of the piezometer cone are also discussed. Factors that influence the interpretations are discussed and guidelines provided. The companion paper, Part I: Sand, considers drained conditions during the test and summarizes interpretation of parameters such as relative density, friction angle, and deformation characteristics of sand. The authors' personal experiences and current recommendations are included. Keywords: static cone penetration testing, in-situ, interpretation, shear strength, modulus, stress history, pore pressures, permeability, consolidation.

Interpretation of cone penetration tests. Part I: Sand

1983 ◽  
Vol 20 (4) ◽  
pp. 718-733 ◽  
Author(s):  
P. K. Robertson ◽  
R. G. Campanella
Keyword(s):  
Shear Strength ◽  
Pore Pressure ◽  
Cone Penetration Test ◽  
Deformation Characteristics ◽  
Penetration Test ◽  
Cone Penetration ◽  
Stress History ◽  
Penetration Testing ◽  
Cone Penetration Testing ◽  
Recent Developments

Significant advances have been made in recent years in research, development, interpretation, and application of cone penetration testing. The addition of pore pressure measurements during cone penetration testing has added a new dimension to the interpretation of geotechnical parameters.The cone penetration test induces complex changes in stresses and strains around the cone tip. No one has yet developed a comprehensive theoretical solution to this problem. Hence, the cone penetration test provides indices which can be correlated to soil behaviour. Therefore, the interpretation of cone penetration data is made with empirical correlations to obtain required geotechnical parameters.This paper discusses the significant recent developments in cone penetration testing and presents a summarized work guide for practicing engineers for interpretation for soil classification, and parameters for drained conditions during the test such as relative density, drained shear strength, and deformation characteristics of sand. Factors that influence the interpretation are discussed and guidelines provided. The companion paper, Part II: Clay, considers undrained conditions during the test and summarizes recent developments to interpret parameters for clay soils, such as undrained shear strength, deformation characteristics of clay, stress history, consolidation characteristics, permeability, and pore pressure. The advantages and use of the piezometer cone are discussed as a separate topic in Part II: Clay. The authors' personal experiences and current recommendations are included. Keywords: static cone penetration testing, in situ, interpretation, shear strength, modulus, density, stress history, pore pressures.

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